Oral Presentation NCGRT/IAH Australasian Groundwater Conference 2019

Building a regional geological model for hydrogeological applications (343)

Anna Bui Xuan Hy 1 , Linda Foster 1 , Renate Sliwa 2 , Fengde Zhou 3 , Joan Esterle 4 , Murray Little 5 , Keith Phillipson 1 , Sanjeev Pandey 1
  1. Department of Natural Resources and Mines, Office of Groundwater Impact Assessment, Brisbane, QLD, Australia
  2. Integrated Geosciences Pty Ltd, Brisbane, QLD, Australia
  3. Arrow Energy Pty Ltd , Brisbane, QLD, Australia
  4. School of Earth and Environmental Sciences, Brisbane, QLD, Australia
  5. Glencore Australia, Brisbane, QLD, Australia

The Office of Groundwater Impact Assessment (OGIA) is responsible for assessing and reporting (UWIR) cumulative groundwater impacts resulting from petroleum and gas activities in the Surat Cumulative Management Area (CMA).

The Surat CMA covers an area of around 300,000 km2 and comprises three geological basins, three main gas reservoirs and two main groundwater aquifers systems – the Great Artesian Basin and the Condamine Alluvium. A comprehensive regional 3D geological model was built by OGIA, using extensive datasets from various sectors: petroleum and gas, mining and groundwater.

The objectives of the geological model are to:

  • Provide a framework for the groundwater flow model to predict impacts
  • Attribute formations for over 35,000 water bores, critical for determining bore impairment, monitoring and extraction
  • Support conceptualisation and hydrogeological investigations.

The methodology adopted for the generation of the 3D geological model using the Petrel E&P Software Platform is a standard approach taken in the petroleum industry. The model is primarily based on the interpretation of geophysical logs (over 7,000 wells) and stratigraphic interpretation of about 25,000 water bores. The model represents the main hydrostratigraphic units at a 250-metre lateral resolution to capture spatial variability over the whole Surat CMA. The model also acknowledges and integrates recent geological mapping, previous local and regional geological models and interpretation of structures and horizons from seismic interpretation sourced from various industry, research and government entities.

The third generation of this model has been successfully developed and used to produce:

  • Grids to develop regional-scale and sub-regional-scale numerical models
  • Aquifer and aquitard mapping and detailed cross-sections for characterisation projects including spring assessment, fault studies and hydrogeological impact assessments
  • Model layering to define aquifer attribution for over 35,000 water bores, including confirmation of monitoring intervals and intake zones for water use supply bores
  • Communication materials for stakeholders and industry.